In portable battery-powered equipment, such as a cellular telephone or other communication device, an external power supply is usually provided so that the user can operate the equipment from household current or vehicle power current in order to conserve battery power. To operate the communication device inside a vehicle, power adapters are commonly designed to fit into the cigarette lighter socket provided in the vehicle. The other end of the power adapter plugs into an external power input connector of the device, or includes what is commonly known in the industry as a "battery eliminator" which replaces a detachable battery coupled to the telephone or communication device.
When operating a cellular telephone or other communication device within a vehicle, it is generally desirable to use an antenna mounted external to the vehicle to improve the performance of the telephone. Some telephones provide a radio frequency (RF) input/output port in addition to the external power input port so that an external antenna may be utilized. However, such a device requires two separate connectors. In other telephones, the external power input port and the RF input/output port are combined within a single connector of the device. However, such a device would typically require that either an external power supply or external antenna be connected.
Accordingly, there is a need to provide a simple, single cable vehicle power adapter which also provides RF input/output capability for connection to an external vehicle antenna.